After modifying one of your own meeting requests, remember to click Send Update to send the updated request to all recipients.

Don't move meeting requests:

Don't move a meeting request from your Inbox to a different folder before you accept or decline the request or before the meeting appears in your calendar. Soon after a meeting request arrives in your Inbox, a piece of Outlook code -- nicknamed the "sniffer" -- automatically adds the meeting to your calendar and marks it as tentative. This is a fail-safe to keep you from missing the meeting in case you don't see the request in your Inbox. However, the sniffer doesn't reply to the meeting organizer. You still need to do that by accepting, accepting as tentative, or declining the request. If you or a rule that you create moves an incoming meeting request from your Inbox before the sniffer can process the request, the meeting never appears in your calendar, and you might miss the meeting.

Get a fresh start:

If a meeting series requires several changes -- a new organizer, a different frequency or time slot, the addition or removal of attendees -- just cancel the series and create a new one. Don't try to modify the original meeting request.